Papers, correspondence and press cuttings relating to Ireland, 1926-1978; Plaid Cymru, 1929-1965; Welsh political, economic and social affairs, 1931-1962; Pantybeiliau Folk School, 1933-1938; world economics, socialism and communism, 1934-1951; and Brittany, 1946; and personal papers, including correspondence, 1924-1978, diaries, 1921-1979, and academic papers, 1922-1946.